The objective of this research was to examine bottlenose dolphin (Tursiops truncatus) habitat use in the Indian River Lagoon (IRL) based on monthly relocation of photo-identified individuals, prey availability and environmental factors from 2003-2015. We focused on the variation of spatial and temporal abiotic and biotic factors and their influence on bottlenose dolphin habitat use patterns. Harbor Branch Oceanographic Institute (HBOI) conducted monthly photo-identification surveys along the length of the IRL and GPS locations of photographed dolphins were collected at the time of surveying. Stratified random samples of prey and environmental variables were collected monthly by the Florida Fish and Wildlife Conservation Commission (FWC) as part of the Fisheries-Independent Monitoring (FIM) program. Kernel density estimation was used to determine the magnitude-per-unit area of dolphins across a continuous raster surface of the IRL by wet and dry seasons each year, the values of which were used as a response variable in Classification and regression tree (CART) analyses with FIM fish community and environmental factors as predictors. Understanding how dolphins respond to environmental factors over time in the IRL could be used to predict future responses in estuaries and prioritize conservation and restoration actions. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Hector�s dolphin (Cephalorhynchus hectori) is an endangered coastal species endemic to New Zealand. Their distribution, like other marine organisms, is intertwined with the dynamics of their local habitats, and at a larger scale, the coastal waters around New Zealand. The main purpose of this thesis was to identify specific habitat requirements of this rare dolphin. Hector�s dolphin distribution around the South Island was quantified along several temporal and spatial scales. Large-scale density analyses of abundance surveys found over half of the South Island�s current population occurred within only three main regions. Two of these strongholds are along the west coast and the third is located around Banks Peninsula on the east coast. Smaller-scale analyses at Banks Peninsula found the majority of the dolphin community was preferentially using core regions within the marine mammal sanctuary. Monthly surveys showed that in summer and autumn statistically more dolphins occurred within inshore regions ([less than or equal to]one kilometre), spread throughout the surveyed coastline. From May through winter, dolphin densities rapidly declined. Remaining dolphins were significantly clumped in more offshore waters of eastern regions. The lowest encounter rates occurred between August and September. Certain 'hotspots' consistently had higher dolphin densities throughout the study period while others were preferred seasonally. To address habitat preferences, surveys simultaneously collected oceanographic samples using a CTD profiler. In general, physical variables of the Peninsula�s eastern and southeastern waters varied less, despite being regularly exposed to upwellings and the varied presence of sub-tropical waters. Semi-sheltered bays and shallow inshore waters were highly variable and more susceptible to spatially discrete influences, such as localised river outflows and exchange events. Several hydrographic features were seasonally predictable due to their dependence on climate. The stratification and location of the two dominant water masses (neritic and sub-tropical) accounted for over half of the temporal and spatial variability observed in oceanographic data. Possible relationships between oceanographic features and aggregations of dolphins within Banks Peninsula were examined using global regression and a spatial technique known as geographical weighted regression (GWR). GWR models out-performed corresponding global models, despite differences in degrees of freedom and increased model complexity. GWR results found relationships varied over localised scales that were concealed by global methods. Monthly GWR models suggested the seasonal presence and strength of local oceanographic fronts influenced dolphin distribution. Dolphin aggregations coincided with the steepest gradients between water masses along eastern regions of the Peninsula, and strong exchange events along the edges of the study area. The continued survival of this endangered species is contingent on its protection. Long-term monitoring programmes are needed for the three main strongholds identified in this study. The occurrence of Hector�s dolphin 'hotspots' along frontal zones within Banks Peninsula also suggests alternative and increased protection strategies are needed for this sanctuary to be effective. In light of this thesis� findings and based on marine protection research, future sanctuaries need to consider why Hector�s dolphins are preferentially using particular regions and how their association with certain oceanographic features can help make informed decisions on more appropriate protected areas.

Whales and dolphins, especially small cetaceans which inhabit rivers and coastal waters, are under the threats from environmental change, habitat destruction, and pollution. Since previous studies haven¡¦t deeply explored the relationship between marine mammal conservation and fishery catches, in this study, we focused on the objective is on the correlation between fishery catches and feeding sources of Chinese white dolphin. About 17 years (1993-2009) of fish catch data from fishery annual reports in the six counties (from Miaoli to Tainan) along the western coast of Taiwan, was used as the data source of the meta-analysis, which set four major prey categories of Chinese white dolphin, i.e., primary prey fish, secondary prey fish, potential prey fish and other prey fish. The study showed the following nine results. First of all, the change of total amount of fish production in six counties was changing irregularly¡Fin recent years, the amount of potential prey fish and other prey fish catches were increasing. Secondly, the decline of primary prey fish was due to the reduced production of Mugilidae . Thirdly, the secondary prey fish catch formed the major catches during 1999-2004 while Sparidae species was the dominated species. The potential prey fish amount was consistent, except in 1994 when Chanidae production was extremely high, making it the major components species. In accordance with Chinese white dolphin distribution hot spot, north hot spot primary prey fish families were Sciaenidae and Trichiuridae. In addition, the amount of south hot spot was irregularly distributing during 1999-2004. For the non-hot spot in the Changhua¡¦s coast, the prey fish production of Mugilidae was decreasing year by year and the non-hot spot in the Tainan¡¦s coast, the prey fish was mainly composed of other prey fish after 2002. However, in these 17 years, the number of fishing vessels increased, yet the total catch decreased. This may imply that the coastal fishery resources is depleted. The discussion on improvement about the fishery annual report and prey resources investigation were also made. At the last, we proposed two suggestions on the issues about hot spot management and enhancing fishery resources restoration.

This dissertation is an investigation of dolphin sound production and distribution off west central Florida. Although a wealth of information exists on the production of common sounds (whistles, echolocation) made by captive, trained dolphins, far less is known about free-ranging dolphin sound production and of unusual sounds. In addition, while inshore dolphin populations or communities are the subjects of research projects in many locations, dolphins in offshore waters are less commonly studied. The objectives of this dissertation were to contribute information on free-ranging dolphin sounds and continental shelf dolphin distribution. While echolocation has been rigorously studied in captive, trained dolphins, there is far less known about how free-ranging dolphins use their echolocation. In order to investigate the use of echolocation by free-ranging dolphins, echolocation recordings from 14 groups of common bottlenose dolphins (Tursiops truncatus) were obtained during towed hydrophone cruises on the West Florida Shelf (WFS) and in Tampa Bay. The mean echolocation pulse rate was inversely related to water depth, suggesting echolocation pulse rate was a function of the two-way travel time of echolocation pulses, which was related to depth. Pulse rate modes were related to potential target distances, and indicated dolphins were commonly echolocating on targets up to at least 91.8 m away. The results of this study indicate that free-ranging bottlenose dolphins are using their echolocation in a manner similar to that found in studies with captive, trained dolphins. Unusual low frequency sounds from bottlenose dolphins were found in the towed hydrophone recordings in Tampa Bay, and the acoustic properties and behavioral contexts of these sounds were investigated. Additional recordings were obtained from Sarasota Bay and Mississippi Sound. These low frequency narrow-band (LFN) sounds were tonal, had peak frequencies between 500 Hz and 1000 Hz, and were produced in trains. Inter-LFN intervals (the time duration between sequential LFN sounds) were significantly longer in recordings from Mississippi Sound. Sounds were correlated with social behavior, and were common during socio-sexual behavior. These sounds were found below optimal hearing range of bottlenose dolphins, and are prone to masking by boats. A combination of autonomous acoustic recorders and visual surveys were used to determine the distribution and sound production patterns on the WFS. Visual surveys supported the results of previous studies indicating that bottlenose dolphins were more common in coastal areas and off of Tampa Bay, while Atlantic spotted dolphins (Stenella frontalis) were more common beyond the 20 m isobath. A single group of rough-toothed dolphins (Steno bredanensis) was observed. Overall, dolphin numbers decreased from inshore to offshore. Acoustic detections mirrored this distribution pattern, however acoustic detections were not as high in coastal regions as expected from the visual survey results, which suggests low sound production rates by coastal dolphins. Atlantic spotted dolphin numbers increased in more northern and inshore waters in spring, suggesting a seasonal migration pattern. Peaks in dolphin sounds in the coastal regions were commonly observed in daylight and evening hours, while in offshore areas sound production peaked at night. This pattern likely reflects foraging activity, and the diel activity cycles of common prey species. Coastal dolphins made proportionately more echolocation than whistles, while the opposite was true for deeper water dolphins. In inshore waters (< 25 m depth), dolphin sound production was generally positively correlated to water temperature (bottom temperature and sea surface temperature) and negatively correlated with chlorophyll, while the opposite pattern tends to occur in deeper waters (> 35 m). This delineation roughly coincides with the distribution patterns of oceanographic properties, prey species distribution, and the distribution of Atlantic spotted dolphins and bottlenose dolphin ecotypes. These results suggest a shift from a benthic based ecosystem to a phytoplankton based ecosystem with increasing depth on the WFS.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Indo-Pacific humpback dolphin (Sousa chinensis) is one of the residential cetaceans in Hong Kong. It is threatened by different anthropogenic activities and one of the threats is the vessel disturbance. According to the past research studies and scientific data, the heavy marine traffic has caused negative impacts to the dolphins, by increasing the risk of boat collisions; creating a noisy environment within the dolphin habitats; causing short-term behavioural changes of dolphins and dolphins may have potential to displace from the Hong Kong waters in the long-term. The current conservation and mitigation measures are inadequate and ineffective towards this situation. An action plan is formulated based on the literature review of the practices from other countries and the results of the questionnaire survey. Mitigation measures such as speed restriction, re-routing or use of technology tools are common measures used by other countries such as the United States or Spain. From the results of the questionnaire survey, the high-speed ferry passengers were willing to spend 23.5 minutes more of their trips for a speed restriction or a longer ferry route in order to reduce the vessel impacts to the dolphins. At the same time, they were willing to pay for HKD 9.26 extra as a surcharge on the ferry fare to serve as a financial support to the dolphin or marine conservation in Hong Kong. It reflected the public had a high willingness to pay for the dolphin conservation in Hong Kong. The action plan summarized the practical mitigation measures according to these findings in order to suggest sound conservation and management measures to the related authorities to mitigate the impacts and to stop the declining trends of dolphin abundance in Hong Kong waters. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Foraging theory suggests that hungry animals balance a complex set of costs and benefits when determining what and how to eat. Prey distribution, patch size, and the presence of conspecifics are important factors influencing a predator's feeding tactics, including the decision to feed individually or socially. Dusky dolphins (Lagenorhynchus obscurus) in New Zealand employ different feeding tactics in varying habitats and seasons. I used programmed survey routes and opportunistic sightings to examine the habitat use and feeding mechanics of dusky dolphins in Admiralty Bay, New Zealand, a protected shallow-water environment frequented by wintering dolphins. I encountered 253 dolphin groups, of which 58.5% were engaged in food-acquisition activities. Photographic efforts revealed a total of 177 individually-recognizable dolphins, 100 of which were returnees from previous seasons. Thirty-seven feeding groups and 70 bouts of feeding behavior were followed. Two-minute interval sampling as well as active acoustic sonar were used to test the hypothesis that diurnally-feeding dolphins would work in a coordinated manner to bring schooling fish to the surface. Feeding tactics observed in Admiralty Bay were then compared to foraging by some of the same animals in the unprotected, deep-water environment off Kaikoura, where large numbers of dusky dolphins feed during the night on organisms associated with a vertically-migrating scattering layer. Evidence supporting coordinated surface feeding was not statistically significant, but indicative of behavioral flexibility in feeding styles as part of a larger feeding repertoire. A potential shift in prey distribution from previous years may also explain some observed patterns. Feeding groups were positively correlated with seabirds and New Zealand fur seals (Arctocephalus forsteri). Mean group size of 6.1 (± 8.23 S.D., n=253) in Admiralty Bay is dramatically less than groups observed off Kaikoura, a variation likely reflecting differences in prey number and distribution, as well as differences in predation risk by deep-water sharks and killer whales. Behavioral flexibility likely confers an adaptive advantage for species subject to environmental fluctuation, whether due to natural or anthropogenic sources. Further research is necessary to evaluate prey distribution in Admiralty Bay and its possible effects on feeding dusky dolphins.

Greater knowledge of the rough-toothed dolphin, Steno bredanensis, is needed to effectively contribute to conservation and management efforts for this species. The primary purpose of this research was to describe ecological and biological parameters for S. bredanensis that will be useful in future assessments of population stress. Several approaches were used to study S. bredanensis, including investigations of free-ranging populations, dead specimens, and captive individuals. Free-ranging rough-toothed dolphins distributed near small oceanic island environments were found to be more commonly sighted in-shore than off-shore. In the Windward islands of French Polynesia, this species preferred water depths of 1000 to 2000m and a distance of 1.8 to 5.5 km from the barrier reef. Group sizes ofrough-toothed dolphins sighted in French Polynesia range between 1 and 35 individuals with a mean size of 12.1. Endocrinology data for S. bredanensis was established in captive healthy and stranded individuals. Ranges and means were provided for progesterone, testosterone, cortisol and thyroid hormones. Changes in thyroid hormone concentrations were reflective of health status and testosterone appeared to be suppressed in ill individuals. Reproduction in S. bredanensis was investigated by determining the size and age range that this species attains sexual and physical maturity. Female rough-toothed dolphins attain sexual maturity by 9 to 10 years of age and males between 5 and 10 years at a similar length of approximately 216 cm. Physical maturity is generally reached at an older age and larger size for both males and females. Ecologically healthy and unheahhy populations of S. bredanensis were described in this investigation and these fmding will be useful in assessing future threats to this species.

Greater knowledge of the rough-toothed dolphin, Steno bredanensis, is needed to effectively contribute to conservation and management efforts for this species. The primary purpose of this research was to describe ecological and biological parameters for S. bredanensis that will be useful in future assessments of population stress. Several approaches were used to study S. bredanensis, including investigations of free-ranging populations, dead specimens, and captive individuals. Free-ranging rough-toothed dolphins distributed near small oceanic island environments were found to be more commonly sighted in-shore than off-shore. In the Windward islands of French Polynesia, this species preferred water depths of 1000 to 2000m and a distance of 1.8 to 5.5 km from the barrier reef. Group sizes ofrough-toothed dolphins sighted in French Polynesia range between 1 and 35 individuals with a mean size of 12.1. Endocrinology data for S. bredanensis was established in captive healthy and stranded individuals. Ranges and means were provided for progesterone, testosterone, cortisol and thyroid hormones. Changes in thyroid hormone concentrations were reflective of health status and testosterone appeared to be suppressed in ill individuals. Reproduction in S. bredanensis was investigated by determining the size and age range that this species attains sexual and physical maturity. Female rough-toothed dolphins attain sexual maturity by 9 to 10 years of age and males between 5 and 10 years at a similar length of approximately 216 cm. Physical maturity is generally reached at an older age and larger size for both males and females. Ecologically healthy and unheahhy populations of S. bredanensis were described in this investigation and these fmding will be useful in assessing future threats to this species.

Hector�s dolphin (Cephalorhynchus hectori) is an endangered coastal species endemic to New Zealand. Their distribution, like other marine organisms, is intertwined with the dynamics of their local habitats, and at a larger scale, the coastal waters around New Zealand. The main purpose of this thesis was to identify specific habitat requirements of this rare dolphin. Hector�s dolphin distribution around the South Island was quantified along several temporal and spatial scales. Large-scale density analyses of abundance surveys found over half of the South Island�s current population occurred within only three main regions. Two of these strongholds are along the west coast and the third is located around Banks Peninsula on the east coast. Smaller-scale analyses at Banks Peninsula found the majority of the dolphin community was preferentially using core regions within the marine mammal sanctuary. Monthly surveys showed that in summer and autumn statistically more dolphins occurred within inshore regions ([less than or equal to]one kilometre), spread throughout the surveyed coastline. From May through winter, dolphin densities rapidly declined. Remaining dolphins were significantly clumped in more offshore waters of eastern regions. The lowest encounter rates occurred between August and September. Certain 'hotspots' consistently had higher dolphin densities throughout the study period while others were preferred seasonally. To address habitat preferences, surveys simultaneously collected oceanographic samples using a CTD profiler. In general, physical variables of the Peninsula�s eastern and southeastern waters varied less, despite being regularly exposed to upwellings and the varied presence of sub-tropical waters. Semi-sheltered bays and shallow inshore waters were highly variable and more susceptible to spatially discrete influences, such as localised river outflows and exchange events. Several hydrographic features were seasonally predictable due to their dependence on climate. The stratification and location of the two dominant water masses (neritic and sub-tropical) accounted for over half of the temporal and spatial variability observed in oceanographic data. Possible relationships between oceanographic features and aggregations of dolphins within Banks Peninsula were examined using global regression and a spatial technique known as geographical weighted regression (GWR). GWR models out-performed corresponding global models, despite differences in degrees of freedom and increased model complexity. GWR results found relationships varied over localised scales that were concealed by global methods. Monthly GWR models suggested the seasonal presence and strength of local oceanographic fronts influenced dolphin distribution. Dolphin aggregations coincided with the steepest gradients between water masses along eastern regions of the Peninsula, and strong exchange events along the edges of the study area. The continued survival of this endangered species is contingent on its protection. Long-term monitoring programmes are needed for the three main strongholds identified in this study. The occurrence of Hector�s dolphin 'hotspots' along frontal zones within Banks Peninsula also suggests alternative and increased protection strategies are needed for this sanctuary to be effective. In light of this thesis� findings and based on marine protection research, future sanctuaries need to consider why Hector�s dolphins are preferentially using particular regions and how their association with certain oceanographic features can help make informed decisions on more appropriate protected areas.